I got an email with the following question, and figured I may as well answer publicly. The question comes from someone who’s an experienced programmer, but has never worked with WordPress before.

[…] I wondered if you had some helpful advice on learning the basics of WP plugin development. I’m mostly hoping there are frameworks/libraries that the community is currently using.

I don’t know of a widely-used library of general WP plugin development tools. Partly this is because WP itself partially qualifies as a “library”, insofar as it provides ready-to-use functions for saving data to the database, URL routing, template loading, user management, etc. And partly it’s because the architecture of WP is so wide open that it’d be difficult to build a more generalized library that covered even a majority of the possible modifications you might make to stock WordPress.

That said, here are a few useful tools that I know of:

• The official WP documentation on writing a plugin is good for learning about plugin manifests as well as a top-level overview of the aspects of plugin development.
• The official Plugin API page is also a good starting point. It explains WP’s hook system, which is the foundation for plugin development.
• Pippin Williamson has written a series called Plugin Development 101 that features a set of video tutorials on common plugin development techniques. Costs a couple bucks, but Pippin is a smart dude and I’m sure the videos are a really good way to get started.
• There are a couple of tools that can be used to generate boilerplate and basic file setup for plugins. The ones I know of are https://github.com/tommcfarlin/WordPress-Plugin-Boilerplate and the wp scaffold plugin command in WP-CLI.
• The book Professional WordPress Plugin Development is very solid, and a good investment for those who like to learn this kinda stuff through books.

My #1 piece of advice to people getting started with WP plugin development is to find a plugin that does something sorta like what they are trying to do and to reverse engineer it. For me, this is far faster and more practical than any hello-world tutorial or sequential set of lessons. YMMV.

If anyone has other suggestions, please feel free to add them in the comments.